Congestive heart failure (CHF) is a medical problem that has significant public health impact on medical care in the US. People with severe CHF are hospitalized frequently and use a large amount of medical resources. CHF is a complex clinical syndrome which is the final common pathway for several forms of cardiac muscle damage. CHF is characterized by the inability of the heart to provide sufficient blood to tissues to meet metabolic needs. During the past 3 decades there have been major advances in the prevention and treatment of cardiovascular disease. However, the incidence and prevalence of CHF are increasing. This is due to an aging society as well as improved survival of patients with acute myocardial infarctions CHF is a clinical syndrome characterized by activation of the sympathetic nervous system and the renin- angiotension-aldosterone system. This is one of the compensatory responses to CHF. An angiotension inhibitor (ACE) reduces the effects of CHF and decreases hospitalization, morbidity and mortality in people with CHF. A selective angiotension II (A II) medication may have additional desirable clinical effects of an ACE inhibitor. This study will monitor subjects potentially receiving both an ACE and A II.